1. Field of the Invention
This invention relates to artificial organs and a method for the manufacture thereof. More particularly, this invention relates to artificial organs such as artificial kidney, artificial lung and plasma separator which effectively function without substantially inducing hemodialysis leukopenia and to a method for the manufacture thereof. This invention further relates to sterilized artificial organs and to a method for the manufacture thereof. It also relates to a medical dialysis membrane which fulfils its function without causing any appreciable secondary effect upon the living system and to a method for the manufacture thereof.
2. Description of Prior Arts
Heretofore artificial organs such as artificial kidney, artificial liver, artificial lung and plasma separator have found acceptance for actual use. Artificial organs, particularly where material exchange is effected as by dialysis, for example, dialysis membranes of hollow-fiber membrane type, flat membrane type, etc. which are made of regenerated cellulose have been used much more than those made of any other material because regenerated cellulose far excels other materials in terms of dialytic property, mechanical strength, cost, etc. The artificial organ which uses membranes of regenerated cellulose such as, for example, the artificial kidney made of regenerated cellulose can inflict upon the patient's body secondary effects such as the so-called hemodialysis leukopenia, a phenomenon that the patient's count of leukocytes shows an abrupt decrease temporary immediately after the dialysis is started. At times, these secondary effects manifested on the patient may be too serious to be ignored.
Recently, membranes of synthetic polymers such as polymethyl methacrylate, polyacrylonitrile, ethylenevinyl alcohol copolymer and polycarbonate have been proposed as membranes permeable to body fluids. In these membranes, the hemodialysis leukopenia is manifested relatively weaker than in the aforementioned membranes of regenerated cellulose. In the membranes of synthetic polymers, however, the physical properties exhibited during assemblage or during service thereof, i.e. their physical strength, thermal resistance and ultrafiltration ratio (UFR), are not well balanced with their behavior in permeation. Thus, these membranes are usable only on a limited number of patients. Moreover, they are expensive and pinholes tend to form during service. Besides, they have specific requirements for the method by which they will be effectively sterilized. As a solution to these problems, there has been proposed the concept of modifying the surface of regenerated cellulose membranes by the use of heparin, for example. This approach, however, has not yet yielded satisfactory results.